Diagnosis & Overhaul - 727, 904, 998 & 999: Description

Transmission combines torque converter with 3-speed gear system. Converter housing and transmission case are aluminum casting. Transmission consists of 2 multiple disc clutches, overrunning clutch, 2 servos and bands, and 2 planetary gear sets to provide 3 forward ratios and reverse ratio. Common sun gear of planetary gear sets is connected to front clutch by driving shell. Driving shell is splined to sun gear and to front clutch retainer. Hydraulic system consists of oil pump and control valve body in which all valves except governor valve are found.

Torque converter is attached to crankshaft through flexible driving plate. Cooling of converter is accomplished by circulating transmission fluid through cooling tubes in radiator lower tank. Torque converter is a sealed unit and cannot be disassembled.

Lock-up clutch is located inside torque converter (if equipped). Lock-up mode is activated only in direct drive and above minimum preset vehicle speed. At wider throttle openings, where 2-3 upshift occurs above minimum lock-up speed, lock-up shift will occur immediately after 2-3 upshift. Lock-up and conventional converters and transmissions are NOT  interchangeable.